This invention relates to the unique placement of a thermostat associated with a protection circuit for a scroll compressor motor.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor, a first scroll member orbits relative to a second scroll member. Each of the scroll members has a base with a generally spiral wrap extending from its base. The wraps interfit to define compression chambers which are reduced in volume as the two orbit relative to each other.
There are many challenges in the design of scroll compressors. One major challenge relates to a loss of charge in the refrigerant system associated with refrigerant compression. In a loss of charge situation, the amount of refrigerant circulating within the refrigerant cycle is reduced, such as by a leak. Under such conditions, continued operation of the refrigerant cycle is undesirable. Other problems in the system can result in increased temperatures within the compressor. One such problem is so-called reverse-rotation, which can occur such as when the motor is improperly wired and runs in a reverse direction.
Motors for compressors in refrigerant cycles, and in particular for scroll compressors are typically provided with a protector circuit. A motor protector circuit includes a switch which opens should a temperature associated with the compressor exceed a predetermined maximum. Thus, should the operating temperature within the compressor exceed the expected normal temperature range, the switch will open. When the switch is open, the motor is stopped, thus stopping operation of the compressor. Recently, systems have been developed wherein a thermostat is associated with a location remote from the motor, and positioned closer to the scroll members. The thermostat is operable to close when a predetermined temperature is reached. When the thermostat closes, current flows to a heater which is positioned near the motor protector switch. This increases the heat at the motor protector switch, and will result in the switch opening potentially at an earlier point than if the thermostat did not add further current to the heater. That is, by positioning the thermostat adjacent to scroll members, the changes in temperature will be more promptly sensed, and the system will be more quickly responsive to undesirable conditions.
The present invention is directed to an improved and preferred placement of the thermostat adjacent the scroll members.
In the disclosed embodiment of this invention, the thermostat has a body mounted partially within a crankcase which supports the orbiting scroll. The thermostat body extends to the thermostat switch itself, which extends into a cavity in the non-orbiting scroll. Preferably, a bias member holds the thermostat body at a position such that it is not subject to rattling. In one preferred embodiment, a cavity is formed within a crankcase tower to receive the thermostat body. The thermostat switch itself is formed in a cap at an upper end of the body. The cap extends into a cavity within the non-orbiting scroll.
The bias member may extends forwardly from the body and abutt an opening in the crankcase in one embodiment. In a second embodiment the bias member is formed between the thermostat switch itself and the cavity in the non-orbiting scroll.
The thermostat may be a single piece, or could include a two-part plug in connection between the switch generally received in the non-orbiting scroll, and an elongate body section received within the crankcase tower. dr
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
FIG. 1 is a view of a prior art scroll compressor.
FIG. 2A is a schematic view of a single phase motor protector circuit.
FIG. 2B is a schematic of a three-phase motor protector circuit.
FIG. 3 shows a first embodiment of the thermostat of this invention.
FIG. 4A is a top view of the FIG. 3 embodiment.
FIG. 4B shows a ledge that supports a portion of the thermostat.
FIG. 5 is a perspective view of the FIG. 3 thermostat.
FIG. 6A is a view of a second embodiment.
FIG. 6B is an exploded view of the FIG. 6A embodiment.
FIG. 6C shows a mounted portion of the FIG. 6A embodiment.
FIG. 6D shows another view of the FIG. 6A embodiment.
FIG. 6E is a perspective view of one portion of the FIG. 6A embodiment.
FIG. 7A shows another embodiment.
FIG. 7B shows another view of the FIG. 7A embodiment.